Remove copied preheader insertion logic from PPCCTRLoops

Now that the preheader insertion logic in LoopSimplify is externally exposed,
use it, and remove the copy-and-pasted version.

No functionality change intended.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@182300 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed